stm32g4: rng: enable common code support

Also fixes an error in the memory map exposed by enabling this.

Reviewed-by: Karl Palsson <karlp@tweak.net.au>

lib/stm32/g4/Makefile

@@ -47,6 +47,7 @@ OBJS += i2c_common_v2.o
 OBJS += opamp_common_all.o opamp_common_v2.o
 OBJS += pwr.o
 OBJS += rcc.o rcc_common_all.o
+OBJS += rng_common_v1.o
 OBJS += spi_common_all.o spi_common_v2.o
 OBJS += timer_common_all.o timer_common_f0234.o
 OBJS += quadspi_common_v1.o